The invention pertains to a lightweight board with two thin-walled top layers and at least one core layer located between the top layers and connected to them, and a process to manufacture this.
A similar lightweight board is known from DE 19506158 A1, in which a core is covered on two sides by at least two boards. This lightweight board has a retaining and finishing profile at its longitudinal sides, which has a base section with a visible, connecting surface and a covering surface located opposite this, and with an anchoring facility located on the covering surface and which engages in the fitted state in the core of the lightweight board. This retaining and finishing profile is pressed into the longitudinal sides of the lightweight board, causing the core of the lightweight board to be damaged at this point, and the retaining and finishing profile is glued to the top layers of the lightweight board with adhesive applied to the anchoring facility.
However, this retaining and finishing profile has the disadvantage that different retaining and finishing profiles must be manufactured for each geometry and shape of the lightweight board, mainly in dependence on the thickness and particularly on the tolerance of the top layers. Another disadvantage of this lightweight board is that the top layers of the lightweight board are pushed or stretched apart when the anchoring facility is pressed into the core layer, which is caused by the different tolerances of the anchoring facility and the different distances between the individual top layers.
A further disadvantage is that this solution can cause the core layer to be detached from one or both of the top layers.
Another similar lightweight board is described in DE 103 13 055 A1. This describes a process and a device to manufacture a lightweight board from two thin-walled top layers which form the upper and lower sides of the board and at least one core layer made of a light filler and located between and glued to the top layers.
The process to manufacture this lightweight board is characterised by the application of an adhesive layer to one side of the core layer in one pass and the subsequent joining of the core layer with the first top layer. An adhesive layer is then applied to the other side of the core layer and the second side of the core layer is joined to the second top layer and the top layers are pressed together with the core layer. It is also described that, to manufacture this lightweight board, frame batons can be located at least at the longitudinal sides of the lightweight board and glued to the top layers. The described lightweight board can therefore be manufactured without frame batons located at the longitudinal sides or with these frame batons at the longitudinal sides. The lightweight board is therefore manufactured with unprotected longitudinal sides and also with frame batons proportioned according to the cross-section and geometry of the lightweight board, which enclose the longitudinal sides. The disadvantage of this process is that although production is to operate continuously, each lightweight board must be assembled step by step as an individual part. Particularly when frame batons are used, the disadvantage is that these must be adapted in their dimensions to the top layers of the lightweight board in production and fully automatic, inline production is therefore unviable. Another disadvantage of the lightweight board is that the frame batons glued to the top layers lead to a situation due to the known production tolerances, particularly in woodworking, in which the core layer does not fully adhere to the top layers and is damaged when pressed to the top layers. For the lightweight board manufactured by this process without glued frame batons, the longitudinal sides must be protected later against damage by additional steps of work and process stages. When the described frame batons are used, it is also necessary to conduct an additional time-consuming and expensive step of work to apply additional covering elements to the longitudinal sides of the lightweight board. The manufacture of these lightweight boards is therefore uneconomical, particularly in view of the fact that it is necessary to protect the longitudinal sides.